Pipe coupling with tongue and groove sealing sleeve

ABSTRACT

A coupler for use in joining two pipes in a butt joint. The coupler includes a band clamp and a split sealing sleeve disposed inside the band clamp for encircling the abutted ends of the pipes. The split sealing sleeve has a tongue-and-groove sealing joint at the confronting free ends of the sleeve. The sealing joint has a member at the mating edges to provide a resilient interference fit of the tongue-and-groove.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.10/871,118 filed Jun. 19, 2004, now U.S. Pat. No. 7,025,393, which is acontinuation of U.S. application Ser. No. 09/886,793 filed Jun. 21,2001, now U.S. Pat. No. 6,758,501, which claims the benefit ofProvisional Patent Application No. 60/213,791 filed Jun. 23, 2000.

TECHNICAL FIELD

This invention relates to pipe couplings; more particularly, it relatesto a type of pipe coupling which is especially adapted for joining twopipe ends in a butt joint. This type of pipe coupling is sometimesreferred to in the trade as a pipe coupler.

BACKGROUND OF THE INVENTION

There is a need, especially in the automotive industry, for a pipecoupling for connecting two pipes together in a vehicle engine exhaustsystem. For example, it is becoming common practice in the repair orservicing of an automobile exhaust system to replace the muffler bycutting the pipe between the muffler and the catalytic converter andattaching a new muffler by use of a special coupling which is hereinreferred to as a coupler. In this example of use, the coupler must becapable of joining two pipes in a butt joint with a good seal againstexhaust gas leakage and which has high pull-apart strength. The use of abutt joint has the advantage of avoiding the need for slotted pipe endsas are commonly used in tail pipe-to-muffler lap joints.

In the prior art, attempts have been made to provide a pipe couplingwhich would meet the requirements of mechanical strength, exhaust gassealing properties and long service life required by the automotiveindustry. However, the prior art leaves much to be desired with respectto the present day requirements.

U.S. Pat. No. 2,227,551 granted Jan. 7, 1941 to Morris describes a pipecoupling which comprises a cylindrical metal sleeve and gasket disposedbetween a clamping shell and the pipes to be coupled together. The metalsleeve is open with confronting ends which have complementary tonguesand recesses which come together when the coupling is tightened.

U.S. Pat. No. 4,056,273 granted Nov. 1, 1977 to Cassel describes acoupling for pipe lap joints which includes a seal ring disposed aboutthe end of the smaller diameter pipe and abutted against the end of thelarger diameter pipe. A clamping device has a clamp band which encirclesand overlaps the end of the larger diameter pipe and the seal ring. Theseal ring includes opposite circumferential ends interengaged with eachother, at least one of the seal ring ends having a ramp surface thatengages the other seal ring end to move the rings axially relative toeach other during clamping of the ring over the inner pipe to therebyprovide sealing of the ring between the ring ends.

A general object of this invention is to provide an improved couplerwhich overcomes certain disadvantages of the prior art.

SUMMARY OF THE INVENTION

According to one aspect of the invention, there is provided a pipecoupling for securing a pair of coaxial pipe ends that comprises a splitsealing sleeve, clamp band and tightening mechanism. The split sealingsleeve includes an inner surface for contacting an outer surface of atleast one of the pipes, an outer surface, a first end having a tongue,and a second end having a groove such that when the first and secondends are drawn together the tongue and groove oppose one another. Thetongue includes first and second spring members separated by a reliefslot, and the groove includes a plurality of convergent side edges.During formation of a non-locking interference fit the tongue penetratesthe groove such that: i) the convergent side edges of the spring membersengage the convergent side edges of the groove, ii) the first and secondspring members are deflected towards each other, iii) the relief slot isdeformed in response to the deflection, and iv) the side edges of thespring members and the groove form a seal against the outer surface ofat least one of the pipes.

According to another aspect of the invention, there is provided a pipecoupling for securing a pair of coaxial pipe ends that also comprises asplit sealing sleeve, clamp band and tightening mechanism. In thisembodiment, the split sealing sleeve includes a tongue with a pluralityof side edges, and a groove with a plurality of side edges and at leastone arcuate relief slot. During formation of a non-locking interferencefit the tongue penetrates the groove such that: i) the side edges of thetongue engage the side edges of the groove, ii) an arcuate side edge ofthe groove is deflected away from an engaging side edge of the tongue,iii) the arcuate relief slot is deformed in response to the deflection,and iv) the side edges of the tongue and the groove form a seal againstthe outer surface of at least one of the pipes.

A complete understanding of this invention will be obtained from thedetailed description that follows taken with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, two illustrative embodiments of theinvention are shown in a pipe coupler especially adapted for use inautomotive vehicle engine exhaust systems. It will be appreciated, asthe description proceeds, that the invention is useful in many differentapplications and in a wide variety of embodiments.

FIG. 1 is a perspective view of a first embodiment of the presentinvention;

FIG. 2 is a cross-sectional view of the coupling of FIG. 1 installed onthe abutted ends of two pipes;

FIG. 3 is a side view of the coupling of FIG. 1 installed on the abuttedends of two pipes;

FIG. 4 is a plan view of a split sealing sleeve in its flat condition;

FIG. 5 is an enlarged view of a first portion of FIG. 4;

FIG. 6 is an enlarged view of a second portion of FIG. 4;

FIG. 7 is a fragmentary view of a split sealing sleeve with tongue andgroove sealing joints in sealing engagement;

FIG. 8 is a plan view of a split sealing sleeve used in a secondembodiment of the invention; and

FIG. 9 is a fragmentary view of a split sealing sleeve of the secondembodiment of the invention showing the tongue and groove sealing jointin sealing engagement.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment ofthe Invention

The first embodiment of the invention is shown in FIGS. 1-7. The coupler10 is adapted to connect a pair of pipes 12 and 14 in a butt joint whichprovides a good gas seal and a strong mechanical connection between thepipes. The pipes 12 and 14 have the same nominal diameter, subject tomanufacturing tolerances. The ends of the pipes 12 and 14 meet at ajuncture 22 in axial alignment with each other. The coupler comprises aclamp 16 which includes a clamp band 18 adapted to encircle the pair ofpipes and overlap the ends of the pipes. The clamp band 18 is formed asan open sleeve and terminates in laterally extending, opposed flanges 19and 21. The clamp 16 also includes a tightening mechanism 24 connectedwith the clamp band for tightening the clamp to reduce thecircumferential length of the clamp band. A split sealing sleeve 26 isdisposed inside the clamp band 18 and has first and secondcircumferential ends 28 and 32 with seal structures, respectively, inconfronting relationship for contact with each other when the splitsealing sleeve is collapsed circumferentially by the clamp band when theclamp is tightened. The sealing sleeve 26 includes a pair of tongue andgroove sealing joints 34 a and 34 b which are provided on theconfronting circumferential ends 28 and 32 of the sealing sleeve 26. Theopening or gap between the confronting ends 28 and 32 of the sealingsleeve 26 is located circumferentially with respect to the clamp band 18so that it does not overlap the gap between the flanges 19 and 21. Whenthe clamp 16 is tightened by the tightening mechanism 24, the sealingsleeve 26 is collapsed circumferentially by the clamp band to cause thetongue and groove sealing joints 34 to close and provide a gas sealagainst leakage to the atmosphere from the juncture 22 of the pipes.

The clamp 16, per se, is of known construction and it is described inU.S. Pat. No. 3,905,623 granted to Cassel granted Sep. 16, 1965 theentire disclosure of which is hereby incorporated by reference into thispatent specification. As stated above, the clamp 16 includes a clampband 18 which is formed as an open sleeve and terminates in laterallyextending opposed flanges 19 and 21. The clamp also includes atightening mechanism 24 connected with the clamp band. The tighteningmechanism comprises a spline or reaction member 23 disposed between theflanges 19 and 21 of the clamp band 18. A pair of bolts 25 extendthrough aligned openings in the flanges and reaction member and a forcebar 27 against which threaded nuts 29 are seated for actuating thetightening mechanism. The coupler 10 will be described in greater detailbelow.

The split sealing sleeve 26 is made of sheet metal, suitably stainlesssteel, and is formed by a stamping operation in flat condition as shownin FIG. 4 and is preformed into a circular sleeve for insertion into theclamp band 18. The tongue and groove joints 34 a and 34 b are disposedin axially spaced relationship on the split sealing sleeve 26 so thatthe juncture 22 of the pipe ends can be disposed between the pair oftongue and groove joints. The tongue and groove joints 34 a and 34 b areof the same construction and will be described with reference to joint34 a as shown in FIGS. 4-6. The joint 34 a comprises a groove 36 a inthe end 28 of the sealing sleeve 26. The groove 36 a is bounded by sideedges 38 a and 42 a which converge toward each other as the depth of thegroove increases from the end 28 of the sealing sleeve. The joint 34 aalso comprises a tongue 44 a which extends from the end 32 of the sleevein alignment with the groove 36 a. The tongue 44 a comprises two springmembers 46 a and 48 a separated by a relief slot 50. The tongue 44 a isformed with convergent side edges 52 a and 54 a on the spring memberswhich converge in the same direction as the side edges 38 a and 42 a ofthe groove 36 a.

The side edges 38 a and 42 a of the groove 36 a are straight except forthe corners at the mouth of the groove and at the bottom of the grooveeach of which is formed with a radius as shown. The side edges of thegroove have an angle of convergence, for example, of about 18 degrees,i.e. each side edge extends at an angle of 9 degrees from the centerline of the groove. The side edges 52 a and 54 a of the tongue 44 aextend in a straight line between respective corners which are formedwith a radius as indicated. When the spring members 46 a and 48 a are inan unstressed or free condition, the side edges 52 a and 54 a have aconvergence angle, for example, of about 12 degrees, i.e. each side edgemakes an angle of 6 degrees with the center line of the tongue 44 a. Therelief slot 50 is suitably of keyhole shape and is disposedsymmetrically with reference to the center line of the tongue. Thespring members 46 a and 48 a are resilient and constitute cantileverspring arms. The spring members are deflected toward each other in theplane of the tongue when they enter the mating groove and maintaincontact with the side edges of the groove 36 a to provide a seal againstgas leakage.

The pipes 10 and 12, as manufactured, have a specified nominal diameterwith a specified allowable tolerance range within which the actual pipediameter may vary. Consequently, pipes 10 and 12 may have the samenominal diameter but have a different actual diameter. The greatestdifference in diameter would occur when one pipe has an actual diameterat the minimum value of the tolerance range and the other pipe has anactual diameter at the maximum value of the tolerance range.

In use, the coupler 10 in its assembled untightened state is positionedover the abutted ends of pipes 12 and 14 with the juncture of the pipeends located between the tongue and groove sealing joints 34 a and 34 b.In this position, clamp 16 is ready for tightening by tightening thenuts 29 on the bolts 25. As the tightening of the clamp 16 progresses,the outer ends of the tongues 44 a and 44 b enter the respective grooves36 a and 36 b and the side edges of the tongues engage the side edges ofthe respective grooves so that there is sliding frictional engagementtherebetween. Assuming that both pipe ends have the same actualdiameter, both tongues will enter the respective grooves to the samedepth of penetration when the tightening of the clamp 16 reaches itsfinal tightening condition. If the actual diameter of both pipes is atthe maximum value of the tolerance range, the penetration will be at aminimum depth with a sealing engagement occurring at points A and B onsealing joint 34 a and at points A and B on sealing joint 34 b as shownin FIG. 7. On the other hand, if the actual diameters of the two pipesare at the minimum value of the tolerance range, then the penetrationwill be at the maximum depth with a sealing engagement occurring atpoints C and D as indicated in FIG. 7. If the actual diameters of thepipes are equal and at an intermediate value in the tolerance range, thedepth of penetration of the tongues will be at a correspondingintermediate depth and sealing engagement will occur at points E and Fin FIG. 7. The spring members 46 a and 48 a of the tongues 44 a and 44 bare deflected by engagement with the respective grooves 36 a and 36 bthroughout the indicated range of penetration. This provides aninterference fit between the side edges of the tongues and grooves whichis effective to maintain a good gas seal. Further, the deflection of thespring members 46 a and 48 a allows tightening of the clamp to transfersufficient clamp loading between the sleeve and pipes to preventrelative movement therebetween and to seal against leakage between theoutside surface of the pipes and the inside surface of the sleeve.

Assume that the two pipes 12 and 14 have different actual diameterswithin the allowable pipe diameter tolerance range. In this situation,when final tightening of the clamp 16 is achieved, one side of it willbe closed farther than the other side and hence the penetration of thetongue and groove joint on one side of the sealing sleeve 16 will begreater than that on the other side. This will cock the sleeve and,depending upon the cock angle, it may be that only one spring member ofeach tongue, instead of both, will engage the respective groove toprovide sealing engagement. Nevertheless, both sealing joints 34 a and34 b are effective to seal against leakage because engagement of onlyone spring member of each tongue with the groove is needed to block gasleakage. Further, because of the resilience of both spring members, thetongue can be compressed during tightening to prevent excessiveinterference that would inhibit adequate clamp closure. Thus, when thetightening of the clamp 16 reaches the final tightening condition theclamp band 18 is stretched around the sealing sleeve 26 and maintains aclamping force which holds the tongue and groove joints in sealedcondition and holds the sealing sleeve sealed against the outer surfacesof the pipes 12 and 14 and the inner surface of the clamp band so thatfluid leakage between the ends of the pipes is blocked from escaping tothe atmosphere.

Second Embodiment of the Invention

A second embodiment of the invention will now be described. The couplerof the second embodiment is of the same construction as the coupler ofFIGS. 1-7 except for a different construction of the split sealingsleeve 26′ which is shown in FIGS. 8 and 9. The sealing sleeve 26′ is ofthe same type as the first embodiment but has only one tongue and groovejoint 60. The joint 60 comprises a groove 62 defined by one end of thesleeve 26′ and a tongue 64 defined by the other end of the sleeve. Thegroove 62 has oppositely disposed side edges 66 a and 66 b. The tongue64 has oppositely disposed side edges 68 a and 68 b. The side edges ofthe groove 62 have an arcuate configuration which extends inwardly ofthe groove such that the groove is wider at its open end and at itsclosed end than it is in the region therebetween. A relief slot 72 a isdisposed adjacent the side edge 66 a and extends in the same directionand thereby forms a spring edge member 74 a. Similarly, a relief slot 72bb is disposed adjacent the side edge 66 b and extends in the samedirection and thereby forms a spring edge member 74 b.

The tongue 64 is rectangular with straight side edges and has a widthsomewhat narrower than the width of the entrance mouth of the groove 62and somewhat greater than the narrowest width between the spring edgesmembers 74 a and 74 b.

In the use of the coupler implemented with the split sealing sleeve 26′,the single tongue and groove joint 60 is closed concurrently with thetightening of the clamp of the coupler in the same manner as describedwith reference to the coupler of FIGS. 1-7. As the tightening of theclamp progresses, the outer end of the tongue 64 enters the groove 62and the side edges of the tongue engage the respective side edges of thegroove so that there is a sliding frictional engagement therebetween.The spring edge members 74 a and 74 b of the side edges of the groove 62accommodate the variation of actual dimensions of the pipes 12 and 14within the manufacturing tolerance range in much the same manner asdescribed with reference to the coupler of FIGS. 1-7. If the two pipeshave actual diameters of equal value, the tongue 64 will penetrate anamount corresponding to the actual diameter and develop sealingengagement with the side edges of the groove. If two pipes havedifferent actual diameters, the sleeve will cock accordingly and theside edges of the tongue will maintain contact with the side edges ofthe groove to provide a seal against leakage through the tongue andgroove joint 62. Also, the spring edge members 74 a and 74 b willprovide engagement without excessive interference that would preventclosing the clamp with tight sealing engagement and transfer ofsufficient clamp loading to prevent relative movement between the pipes.

Although the description of this invention has been give with referenceto particular embodiments, it is not to be construed in a limitingsense. Many variations and modifications of the invention will now occurto those skilled in the art.

As used in this specification and appended claims, the term “forexample” and the verbs “comprising,” “having,” “including,” and theirother verb forms, when used in conjunction with a listing of one or morecomponents or other items, are each to be construed as open-ended,meaning that that the listing is not to be considered as excludingother, additional components or items. Other terms are to be construedusing their broadest reasonable meaning unless they are used in acontext that requires a different interpretation.

1. A pipe coupling for connecting two pipe ends, comprising: a clampband extending circumferentially from a first end to a second end; atightening mechanism located at said first and second ends of said clampband, said tightening mechanism including at least one fastener totighten said clamp band by drawing said first and second ends towardseach other; and a split sealing sleeve located radially inside saidclamp band in contact with said clamp band, said split sealing sleevehaving first and second circumferential ends in confronting relationshipfor contact with each other when said sealing sleeve is collapsedcircumferentially by tightening of said clamp band, said sealing sleeveincluding at least one tongue and groove sealing joint, said groovebeing defined at one circumferential end of the sealing sleeve and saidtongue being defined at the other circumferential end of the sealingsleeve, said tongue being disposed opposite said groove for mating withsaid groove when said sealing sleeve is collapsed circumferentially, thetongue and the groove each having first and second side edges, the firstside edge of the tongue and the first side edge of the groove being afirst mating-pair of side edges, the second side edge of the tongue andthe second side edge of the groove being a second mating-pair of sideedges, said tongue having a non-locking interference fit with saidgroove throughout a range of penetration extending from initialengagement to a point of maximum penetration for both of saidmating-pairs, wherein a central portion of at least one of said firstside edges is non-parallel relative to a circumferential centerline ofsaid sleeve, said sealing sleeve including a relief slot adjacent one ofsaid first side edges forming a spring member which yields in responseto penetration of said tongue into said groove, the width of said tonguebefore insertion into said groove being greater than the width of saidgroove, wherein forceful penetration of said tongue into said grooveduring tightening of said clamp band causes engagement of saidnon-parallel first side edges with each other and said second side edgeswith each other which, during further tightening of said clamp, causessaid sealing sleeve to deform at said relief slot as said tonguepenetrates into said groove.
 2. A pipe coupling as defined in claim 1,wherein said split sealing sleeve includes two tongue and groove sealingjoints which are axially spaced apart.
 3. A pipe coupling as defined inclaim 2, wherein said two sealing joints are spaced apart on oppositesides of said circumferential centerline.
 4. A pipe coupling as definedin claim 2, wherein said spring member comprises one of two springmembers that together comprise the tongue in the first joint, andwherein the tongue in the second joint also comprises two springmembers.
 5. A pipe coupling as defined in claim 1, wherein said springmember is a cantilever spring arm.
 6. A pipe coupling as defined inclaim 1, wherein said spring member is a unitary strip of arcuate shapeextending along said relief slot.